The Mercedes-Benz C43 AMG uses 12174NA or 2357NA bulbs for front turn signals and 12496 or PY21W bulbs for rear turn signals, with each size corresponding to specific vehicle configurations. The replacement chart covers 1998 through 2019 model years and details bulb size specifications across the vehicle's production range.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz C43 AMG front turn signal uses the 12174NA bulb for the 2017-2019 model years, specifically in vehicles equipped with halogen capsule headlamps. This bulb is identified by an OEM part number rather than an ANSI or ECE standard designation, and it features natural amber glass with a 12V rating.
The 2357NA bulb appears in the front turn signal position for the 1998-2000 C43 AMG. It follows the ANSI standard used in the United States and Canada, operates at 12V, and carries a dual-filament design rated at 26.9W and 8W respectively, mounted on a BAY15d bayonet base.
The dual-filament construction of the 2357NA means the bulb serves two distinct brightness levels from a single unit. The BAY15d base features two offset pins at different heights, which prevents incorrect installation and distinguishes it from single-filament bayonet bases.
The rear turn signal position on the C43 AMG uses either the 12496 or PY21W bulb depending on the model year, and the two are not the same type. The 12496 is a Philips/Osram part number for a 12V halogen specialty bulb, while the PY21W is an ECE-standard single-filament amber bulb rated at 12V and 21W.
The PY21W uses a BAU15s bayonet base, which has two pins at the same height but offset at an angle of 150 degrees. This offset base is intentionally incompatible with the standard BA15s base, preventing substitution with non-amber bulbs in markets where amber turn signals are legally required.
For the 2018 C43 AMG rear turn signal with halogen capsule headlamps, the specified bulb is the PY21W, while the 2017 and 2019 model years in the same configuration use the 12496. This means the rear turn signal bulb type is not uniform across the 2017-2019 generation.
The 1998-1999 rear turn signal specifications also differ between those two years. The 1998 C43 AMG uses the 12496, as does 1999, though the 2000 model year shifts to the PY21W for the same position.
The natural amber glass designation on both the 12174NA and 2357NA bulbs indicates that the amber color is produced by the glass coating rather than by an amber lens in the housing. This distinction affects how replacement bulbs must be selected, since a clear bulb in the same base type would not replicate the original amber output.